.login-form {
    max-width: 300px;
    position: fixed;
  }

  .login-form-forgot {
    float: right;
  }

  .login-form-button {
    width: 100%;
  }
.logo {
      /*flex 布局*/
      display: flex;
      /*实现垂直居中*/
      align-items: center;
      /*实现水平居中*/
      justify-content: center;
      
      text-align: justify;
      width:200px;
      height:200px;

      margin:5px auto;
      
}